The present invention relates in general to a method of testing body components of pulsed droplet deposition apparatus. The body components with which the invention is particularly concerned each comprise a sheet of piezoelectric material formed with a multiplicity of parallel channels having upstanding channel dividing side wall elements poled in a direction normal to said sheet and each plated on opposite channel facing wall surfaces thereof with electrodes.
The related patent applications describe various forms of pulsed droplet deposition apparatus. One form described employs a body component of the kind referred to above and a further body component comprising a sheet of inactive material bonded to the free ends of the channel dividing side walls to form the channel array, the channels of which are of rectangular transverse cross-section. In this form, the channel dividing side walls form monolithic cantilever actuators which are displaceable by electrical impulses applied to their electrodes to impart pressure impulses to droplet liquid in the channels for effecting droplet ejection from the channels. Such droplet ejection takes place through nozzles which communicate with the respective channels of the array.
In another form of droplet deposition apparatus described in the related patent applications, the channel dividing side walls of two like body components are bonded together at the free ends thereof to form the channel array. In this form of channel array, a voltage impulse applied to the electrodes of the channel dividing side walls deflect the side walls in shear mode into chevron formation. Pressure pulses are thereby imparted to the droplet liquid in the channels into which said channel dividing side walls are deflected for ejection of droplets from the respective channels of the array.
In both of the forms of pulsed droplet deposition apparatus, which in practice are drop-on-demand ink jet printers, each channel dividing wall actuator may serve both channels on opposite sides thereof; that is to say, each can be deflected in opposite senses to effect droplet ejection from the respective channels on opposite sides thereof.
It will be apparent that body components of the kind referred to above are vital components of the pulsed droplet deposition apparatus described in the related patent applications. It is important therefore that a procedure for reliably testing such body components in the initial stages of the manufacturing process be available so that early rejection of imperfect specimens can take place.